JP2000297373A - Sliding member and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member having a low friction coefficient and excellent in wear resistance by making it into the one whose solid lubricity effectively functions even in lubricating oil. SOLUTION: As to a hard carbon film sliding member 1 the surface of a base material 2 is coated with a hard carbon film 3 by vapor phase synthesis, which is thereafter subjected to plasma treatment or ion implantation, by which the surface of the hard carbon film 3 is incorporated with nitrogen and/or oxygen and/or is provided with the hard carbon film 3 in which the content of hydrogen in the surface is controlled to <=10 at%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member having a low friction hard carbon film, and more particularly to a sliding member having a low friction hard carbon film suitable for use in lubricating oils such as engine oil and transmission oil. The present invention relates to a member and a method for manufacturing the member.

[0002]

2. Description of the Related Art A hard carbon film is an amorphous carbon film or a hydrogenated carbon film, and includes aC: H (amorphous carbon or hydrogenated amorphous carbon), iC
(Eye carbon) and DLC (diamond-like carbon or DLC).

For the formation, a gas phase synthesis method such as a plasma CVD method for forming a film by decomposing a hydrocarbon gas by plasma, or an ion beam evaporation method using carbon and hydrocarbon ions is used. This hard carbon film has a high hardness, a smooth surface, and excellent wear resistance, and has a low friction coefficient and excellent low friction performance due to its solid lubricity. The friction coefficient of a normal smooth steel surface without lubrication is 0.5 to 1.0, whereas the friction coefficient of a hard carbon film without lubrication is about 0.1.

At present, utilizing these excellent properties, processing jigs such as cutting tools and grinding tools including drill blades, and non-lubricating tools such as plastic working dies, valve cocks and capstan rollers. Application to sliding parts and the like below is being planned.

[0005] Further, with respect to mechanical parts such as an internal combustion engine that slides in lubricating oil, there is a growing demand for reducing mechanical loss as much as possible from the viewpoint of energy consumption and environmental problems. It is desired that the hard carbon film having the solid lubricating property reduce friction in a portion where dynamic conditions are severe.

[0006]

However, when the above-mentioned hard carbon film is coated on a sliding member and slid in a lubricating oil such as engine oil or transmission oil, the sliding member has a certain degree of low smoothness. Sliding members that have been subjected to friction but have a hard coating treatment that does not have solid lubricating properties, such as titanium nitride (TiN) and chromium nitride (C
The problem has been clarified that the sliding member which has been subjected to the ion plating film treatment of (rN) shows only low friction performance equivalent to that of the sliding member.

That is, a conventional sliding member treated with a hard carbon film has the same surface roughness in a lubricating oil and does not have the solid lubricating property even though the sliding member has a solid lubricating property. The problem is that the frictional performance is equivalent to that of a super-finished steel member.

For example, three 3/8 inch balls are pressed in a lubricating oil with a load of 1 kgf, and the pressure is set to 0.03 m / sec.
When sliding at a relative speed of?, Diamond-like carbon as a hard carbon coating has a friction coefficient of 0.08 to 0.12.
The lubricating oil has the same coefficient of friction in a lubricating oil as compared with a steel material or a chromium nitride (CrN) ion-plated film having the same surface roughness and no film treatment.

Also, molybdenum disulfide (MoS ₂ ) or polytetrafluoride having a solid lubricating property in a lubricating oil such as an engine oil or a transmission oil so as to realize a low friction with a friction coefficient μ = 0.07 or less. Sliding parts whose surface is treated with ethylene (PTFE) have already been applied in many cases, but when used under severe sliding conditions under high surface pressure, the abrasion resistance is insufficient and the performance is initially low. Although it can be achieved, there has been a problem in that when it is used for a long time, it is worn and its performance cannot be maintained.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of these problems and is directed to a sliding member having a surface treated with a hard carbon film containing nitrogen and / or oxygen, or a hydrogen content. Is a sliding member treated with a hard carbon coating of 10 at% or less, its solid lubricity works effectively even in lubricating oil, and has a low friction coefficient μ = 0.07 or less and abrasion resistance. It is an object of the present invention to provide a sliding member having excellent performance.

[0011]

There have been few reports on the frictional properties of hard carbon films in lubricating oils, and there have been many unknowns. The effects of oxygen and hydrogen concentrations on the friction characteristics in lubricating oils have been studied and clarified, and the nitrogen, oxygen and hydrogen concentrations of the hard carbon coating that can achieve low friction in lubricating oils have been defined. Has succeeded in realizing low friction performance with a friction coefficient μ in a lubricating oil of 0.07 or less.

That is, in the sliding member according to the present invention, as described in claim 1, in a sliding member used in lubricating oil, at least a surface layer comprises a hard carbon film, It is characterized in that the surface contains nitrogen and / or oxygen.

[0013] Similarly, the hard carbon film sliding member according to the present invention is a sliding member used in lubricating oil, wherein at least the surface layer is made of a hard carbon film, It is characterized in that the surface is made of a hard carbon film having a hydrogen content of 10 at% or less.

Further, in the embodiment of the hard carbon film sliding member according to the present invention, as described in claim 3, the hard carbon film is made of vapor phase synthetic diamond. I have.

[0015] Similarly, in the embodiment of the hard carbon film sliding member according to the present invention, the nitrogen and / or oxygen content of the surface of the hard carbon film is 0.5 at%. It is characterized by the above.

Similarly, in the embodiment of the hard carbon film sliding member according to the present invention, as set forth in claim 5, the hard carbon film surface has a nitrogen and / or oxygen content of 30 at% or less. It is characterized by having something.

Similarly, in the embodiment of the hard carbon film sliding member according to the present invention, as described in claim 6, the nitrogen and / or oxygen content of the hard carbon film surface is at least 4 at% and at least 20 at. % Or less.

Similarly, in the embodiment of the hard carbon film sliding member according to the present invention, as described in claim 7, the surface roughness is not more than Ra 0.1 μm. I have.

Similarly, the embodiment of the hard carbon film sliding member according to the present invention is characterized in that the surface hardness is Hv 1000 or more, as described in claim 8.

Similarly, in the embodiment of the hard carbon film sliding member according to the present invention, the thickness of the hard carbon film is 1 μm or more and 10 μm or less, and It is characterized in that the coefficient of friction in oil is 0.07 or less.

Similarly, in the embodiment of the hard carbon film sliding member according to the present invention, the adjusting shim of the valve mechanism of the internal combustion engine is constituted as described in claim 10. It is characterized by.

[0022] The method of manufacturing a hard carbon film sliding member according to the present invention is as described in claim 11.
In manufacturing the hard carbon film sliding member according to any one of (1) to (10), a hard carbon film is coated on the surface of the base material by gas phase synthesis, and then plasma treatment or ion implantation is performed.

[0023]

Since the hard carbon film sliding member according to the present invention has the above-mentioned structure, a large amount of polar groups can be present on the surface, so that the oily additive contained in the lubricating oil is physically adsorbed on the surface. Or, it becomes easy to chemically adsorb, and a hard carbon film sliding member having a low friction of μ = 0.07 or less in a lubricating oil can be obtained.

If the nitrogen and / or oxygen concentration on the surface is less than 0.5 at%, low friction in the lubricating oil tends to be hardly realized, and conversely, 30 at
%, The abrasion resistance under a high surface pressure tends to be insufficient. Therefore, the upper limit is preferably 30 at%. More preferably, the content is set to 4 at% to 20 at% so that low friction characteristics in a lubricating oil can be obtained without deteriorating wear resistance and smoothness.

The plasma treatment for causing the surface to contain nitrogen and / or oxygen can be performed using an apparatus as shown in FIG.

That is, the plasma processing apparatus 2 shown in FIG.
1 has a vacuum chamber 22 and a base holder 24 for holding a base 23 constituting a sliding member below the inside of the vacuum chamber 22. The base holder 24 is connected to a bias power supply 25. I have. In addition, RF
An electrode 26 is provided. An RF power source 27 is connected to the RF electrode 26, and the plasma forming gas in the gas cylinder 28 can be supplied through a gas flow controller 29. A discharge plasma 30 is formed between the RF electrodes 26, and ions 32 are formed at the aperture 31 so that the radical ion beam 33 reaches the base material 23. It can be evacuated in the direction A via a vacuum pump. Then, using such a plasma processing apparatus 21, for example, RF input power: 10 to 100
W, gas flow rate: 5 to 50 cc / min, bias voltage:
The present invention can be implemented in the range of -250 to + 250V.

On the other hand, although it is very difficult to detect the hydrogen concentration, by setting the hydrogen content to 10 at% or less, low friction in the lubricating oil can be realized. In order to reduce the hydrogen content to 10 at% or less, at least a hard carbon film coated with an amorphous carbon film manufactured by a carbon ion beam method or the like without using a hydrocarbon gas plasma at the time of film formation or a polycrystalline diamond film formed by a thermal CVD method Preferably, it is a sliding member.

The surface roughness is preferably set to Ra 0.1 μm or less in consideration of low friction characteristics and aggressiveness to a partner, and the surface hardness is preferably set to Hv 1000 or more at which abrasion resistance can be secured. Furthermore, the film thickness is 1 μm
If the thickness is smaller than this, the adhesion strength is insufficient, and if the thickness is larger than 10 μm, the residual stress in the film increases, and the film may be spontaneously peeled off.

It is preferable that such a hard carbon film sliding member constitutes, for example, an adjusting shim of a valve train of an internal combustion engine, if necessary.

[0030]

According to the sliding member of the present invention, at least the surface layer of the sliding member used in the lubricating oil is made of a hard carbon film. Since the surface of the carbon film contains nitrogen and / or oxygen, it is possible to effectively function its solid lubricity even in a lubricating oil, so that it has excellent lubricity and wear resistance. A remarkable effect that it is possible to provide a hard carbon film sliding member having a long life is provided.

According to a second aspect of the present invention, in the sliding member used in the lubricating oil, at least the surface layer is made of a hard carbon film, and the surface has a hydrogen content of 10a.
Since the hard carbon film is made of a hard carbon film having a thickness of t% or less, the solid lubricating property can be effectively functioned even in a lubricating oil. The great effect that a moving member can be provided is brought about.

And, as described in claim 3,
By making the hard carbon film a vapor phase synthetic diamond, it is possible to provide a hard carbon film sliding member having a high hardness, a smooth surface and excellent wear resistance. Is brought.

Further, as described in claim 4, the nitrogen and / or oxygen content of the surface of the hard carbon film is set to 0.1.
When the content is 5 at% or more, a remarkable effect that low friction in lubricating oil can be more stably obtained is obtained.

Furthermore, by setting the nitrogen and / or oxygen content of the surface of the hard carbon film to 30 at% or less, the wear resistance under a high surface pressure is reduced. A remarkable effect of being able to be more stable and sufficient is provided.

Further, as described in claim 6, by setting the nitrogen and / or oxygen content of the hard carbon film surface to 4 at% or more and 20 at% or less, low lubricating oil can be obtained. A remarkable effect is obtained that it is possible to provide a hard carbon film sliding member in which the friction can be obtained more stably and the wear resistance under a high surface pressure is more stable and sufficient.

Further, as described in claim 7, when the surface roughness is Ra 0.1 μm or less, it is possible to achieve a low friction and a small aggressiveness to a partner. A great effect is brought.

Further, as described in claim 8, by setting the surface hardness to Hv1000 or more, it is possible to sufficiently secure the wear resistance. A great effect is brought.

Further, as described in claim 9, the thickness of the hard carbon film is 1 μm or more and 10 μm or less, and the friction coefficient in lubricating oil is 0.07 or less. Accordingly, it is possible to provide a low-friction sliding member having excellent durability, which can improve the density strength with respect to the base material and reduce the residual stress in the film to eliminate the risk of peeling. This is a great effect that is possible.

Furthermore, by forming an adjusting shim of the valve train of the internal combustion engine, the mechanical loss in the valve train can be reduced. There is a significant effect of being possible.

According to the method of manufacturing a hard carbon film sliding member according to the present invention, as described in claim 11, in manufacturing the hard carbon film sliding member according to any one of claims 1 to 10, Since the substrate surface is coated with a hard carbon film by gas phase synthesis and then subjected to plasma treatment or ion implantation, even in a lubricating oil, it is possible to make its solid lubricity function effectively. A remarkable effect that it is possible to produce a hard carbon film sliding member having excellent wear resistance and wear resistance is provided.

[0041]

EXAMPLES Examples of the present invention will now be described in detail along with comparative examples, but it goes without saying that the present invention is not limited to only such examples.

In a sliding member 1 as shown in FIG. 1, a hard carbon film 3 is coated on a disk base material 2 having a diameter of 30 mm and a thickness of 4 mm. The test was performed. The sliding member 1 constituting this test piece had a hard carbon film 3 formed on a disk base material 2 according to the specifications shown in Table 1.

Example 1 In Example 1, a vapor-phase synthetic diamond film was deposited to a thickness of 10 μm on a ceramic disk substrate made of silicon nitride by a thermal CVD method. A sliding member finished to a surface roughness Ra of 0.05 μm by polishing with abrasive grains was produced.

(Example 2) In Example 2, carburizing steel (JI
S SCM415) with a steel substrate surface of Ra0.0
After super-finishing to 4 μm, a hard carbon film is coated by an ion plating method using a carbon ion beam.
A 0.09 μm sliding member was produced.

(Embodiment 3) In the embodiment 3, the surface of the sliding member of the embodiment 2 is wrapped to have a surface roughness Ra of 0.03 μm.
It was finished.

Example 4 In Example 4, a steel for carburizing (JI
S SCM415) with a steel substrate surface of Ra0.0
After super-finishing to 4 µm, diamond-like carbon (D
LC) After the film was formed on the substrate, a film having a surface containing oxygen was further produced using the plasma processing apparatus shown in FIG. At this time, oxygen plasma treatment was performed under the conditions of RF input power: 50 W, oxygen gas flow rate: 10 cc / min, and bias voltage: -100 V. The oxygen content of the surface of the hard carbon film thus obtained was about 3.5 at%.

(Embodiment 5) In Embodiment 5, a sliding member is obtained by performing the same plasma oxygen treatment as in Embodiment 4 on the hard carbon film member of Embodiment 3. The oxygen content of the surface of the hard carbon film thus obtained was about 3.5 at%.

Example 6 In Example 6, the polycrystalline diamond film of Example 1 was subjected to nitrogen plasma processing, and the plasma processing conditions were the same as in Examples 4 and 5.
The oxygen content on the surface of the hard carbon film thus obtained was about 5.7 at%.

(Comparative Example 1) In Comparative Example 1, a steel for carburizing (JI
S The surface of the substrate made of SCM415) is Ra0.24.
After grinding to μm, it was treated with a manganese phosphate salt.

(Comparative Example 2) In Comparative Example 2, a steel for carburizing (JI
The surface of the base material composed of S SCM415) is Ra0.04.
It has been super-finished to μm.

Comparative Example 3 In Comparative Example 3, chromium nitride (CrN) having a hardness of Hv1500 and a thickness of 2.0 μm was further applied to the sliding member of Comparative Example 2 by an ion plating method.
This is a coating of the film.

Comparative Example 4 In Comparative Example 4, a polycrystalline diamond film was formed on a silicon nitride substrate by a thermal CVD method and had a surface roughness of Ra 0.12 μm.

(Comparative Example 5) In Comparative Example 5, the steel for carburizing (JI
The surface of the base material composed of S SCM415) is Ra0.04.
μm, and then diamond-like carbon (DL) using hydrocarbon gas with a plasma CVD device.
C) A film formed on a substrate.

(Comparative Example 6) In Comparative Example 6, a steel for carburizing (JI
S SCM415) The surface of the substrate made of Ra0.20
After grinding to μm, a hard carbon film was coated by an ion plating method using a carbon ion beam. In this case, the surface roughness of the film after film formation is Ra of 0.25 μm.

Comparative Example 7 Comparative Example 7 is a sliding member in which the hard carbon film member of Comparative Example 6 was subjected to the same plasma oxygen treatment as in Example 4. The oxygen content on the surface of the hard carbon film obtained as described above was about 40 at%.

(Test Example) In conducting a friction test, a friction coefficient was measured using a pin-on-disk type friction tester 41 as shown in FIG. 3 as a friction test apparatus.

In the friction test apparatus 41, a work table 43 rotatably supported by a rotating shaft 42 is arranged, and the slide member 1 as a test piece is installed on the work table 43. 3/8 inch bearing S on top side
Three UJ2 balls 44 are arranged and pressed by a spring 45 with a load of 1.0 kgf.

Then, the ball 44 is attached to the ball holder 46.
The rotation shaft 42 is connected to a motor 47 and is driven to rotate relative to the ball 44 at a relative sliding speed of 0.01 to 0.1 m / sec. The load cell 48 measures a torque according to a frictional force generated between the moving member 1 and calculates a friction coefficient. In addition, the test piece sliding member 1
Is immersed in the lubricating oil 49, an oil bath 50 is set, and the oil temperature is set to 80 ° C. by an oil temperature control unit (not shown). The lubricating oil 49 is commercially available engine oil 5W-30SG.
This was performed using

The sliding members of Examples and Comparative Examples shown in Table 1 were arranged as the test piece sliding members 1 of the friction tester 41, and the results of measurement of the friction coefficient in the lubricating oil 49 are shown. For reference, the results of measurement of the friction coefficient when lubricating oil is not put in the oil bath, that is, without lubrication under the same load and sliding speed conditions are also shown. The test conditions at this time were: load applied to three balls 44: 1 kgf,
The sliding speed was set at 0.25 m / sec (250 rpm).

[0060]

[Table 1]

As can be seen from the measurement results of the coefficient of friction shown in Table 1, the hard carbon film was compared with Comparative Example 2 having no film due to its solid lubricating property and no film having solid lubricating property under lubrication. Low compared to Example 1 and Comparative Example 3.

However, the diamond-like carbon film of Comparative Example 5, which contained more than 10 at% of hydrogen in the lubricating oil, had the same friction coefficient as those of Comparative Examples 1 and 2 having no coating treatment, and also contained hydrogen. Even when the surface roughness is Ra 0.10 μm or more, the coefficient of friction becomes 0.07 or more and the effect of reducing the friction is small even in the polycrystalline diamond film or the amorphous carbon film of Comparative Example 4 in which the amount is 10 at% or less.

On the other hand, when the content of hydrogen is 10 at%
Below, and / or Examples 1 to 6 containing nitrogen or oxygen on the surface and having a surface roughness Ra of 0.10 μm or less, all have a friction coefficient of 0.07 or less. It can be seen that the friction loss can be effectively reduced.

Further, the carbon hard film member of Example 5 is shown in FIG.
The friction loss torque per cam when used in an adjusting shim of a valve mechanism of an internal combustion engine as shown in FIG. The torque was measured with a torque meter attached to a camshaft shaft (not shown).

In the valve train of the internal combustion engine shown in FIG.
A cam shaft 52 having a cam 51 is driven to rotate by a timing belt (not shown). The valve 53 is inserted into a valve guide 54, and a valve lifter 55 is provided above the shaft end of the valve 53. A valve spring 57 is provided between the cylinder head 56 and the valve lifter 55 by a retainer 58 and a cotter 59.
Thus, a load is applied in a direction in which the valve 53 is closed. An adjusting shim 60 is fitted above the valve lifter 55 and the cam 51
Is adjusted by the thickness of the adjusting shim 60 so that the clearance with the adjusting shim 60 becomes about 0.3 mm, and the cam 51 rotates by driving the camshaft shaft 52, and slides on the adjusting shim 60 to reciprocate the valve 53. It is a mechanism to exercise.

The test conditions were as follows: camshaft rotation speed: 300 rpm
(At idling), Spring Max load: 50kg
f, Engine oil temperature: 80 ° C., the surface roughness of the mating cam 51 slidably in contact with the adjusting shim 60 was super-finished, and finished to Ra 0.05 μm.

For comparison, in addition to the above Example 5, the sliding members of Comparative Examples 1 and 2 which were conventionally used, the sliding member of Comparative Example 3 treated with a chromium nitride film, and the hard carbon film treated Similarly, the torque loss when the sliding member of Comparative Example 5 was used for the adjusting shim 60 was measured under the same conditions. FIG. 5 shows the measured results.

As can be seen from the results shown in FIG. 5, even with the same surface roughness, the adjusting shim of Example 5 had smaller friction loss torque and was superior in friction performance as compared with the comparative example. .

[Brief description of the drawings]

FIG. 1 is an explanatory view of a slope of a sliding member having a hard carbon film on a substrate surface.

FIG. 2 is an explanatory sectional view of a plasma processing apparatus.

FIG. 3 is an explanatory sectional view of a friction test apparatus for performing a friction test in a lubricating oil.

FIG. 4 is an explanatory sectional view of a valve mechanism of an internal combustion engine.

FIG. 5 is a graph showing measurement results of friction loss torque.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Kano Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Inventor Yutaka Mabuchi Yutaka 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. F term (reference) 3G016 AA06 AA19 BB05 EA00 EA03 EA24 FA18 FA21 GA02 3J030 EA21 EB07 EB09 EC01 EC04 EC07 4K030 BA28 CA02 CA05 DA08 FA10 JA01 LA23

Claims (11)

[Claims] 1. A sliding member used in lubricating oil, wherein at least a surface layer is made of a hard carbon film, and the surface of the hard carbon film contains nitrogen and / or oxygen. Moving member. 2. A sliding member used in lubricating oil, wherein at least the surface layer is made of a hard carbon film and the surface has a hard carbon film having a hydrogen content of 10 at% or less. Sliding member. 3. The sliding member according to claim 1, wherein the hard carbon film is a vapor phase synthetic diamond. 4. The hard carbon film sliding member according to claim 1, wherein the nitrogen and / or oxygen content on the surface of the hard carbon film is 0.5 at% or more. 5. The hard carbon film sliding member according to claim 1, wherein the surface of the hard carbon film has a nitrogen and / or oxygen content of 30 at% or less. 6. The hard carbon film sliding member according to claim 1, wherein the surface of the hard carbon film has a nitrogen and / or oxygen content of 4 at% or more and 20 at% or less. 7. The hard carbon film sliding member according to claim 1, wherein the surface roughness is Ra 0.1 μm or less. 8. The hard carbon film sliding member according to claim 1, wherein the surface hardness is Hv1000 or more. 9. A hard carbon film having a thickness of 1 μm or more and 10 μm or more.
m and a coefficient of friction in lubricating oil of 0.07
The hard carbon film sliding member according to any one of claims 1 to 8, wherein: 10. The hard carbon film sliding member according to claim 1, which constitutes an adjusting shim of a valve mechanism of an internal combustion engine. 11. A hard carbon film sliding member according to any one of claims 1 to 10, wherein a hard carbon film is coated on the surface of the base material by gas phase synthesis, and then plasma treatment or ion implantation is performed. A method for producing a hard carbon film sliding member, characterized in that: